The present invention relates to a creeping discharge lightning protection device (arrestor) for preventing breaking of insulated wire and momentary service interruption of power system due to lightning surge arising close on supporting insulator in overhead power lines.
A breaking of insulated wire typically rises out of a mechanism such that a lightning surge first causes the destruction of an insulating sheath adjacent a supporting insulation, an AC dynamic then being caused by a flashover in a multiple-phase power line, this AC short-circuit current then passing regionally through the damaged portion via an metallic arm securing the supporting insulation, and a conductor layer of the insulated wire eventually being evaporated or broken by a heat caused by arcing. A momentary service interruption of a power system arises from a continuous earth current due to a flashover in the supporting insulation by the lightning surge. For preventing the breaking and momentary service interruption, it is important to interrupt the AC short-circuit current and earth current caused along a discharging path formed by the lightning surge.
Currently, a ZnO element is installed as a most typical measure to prevent the breaking and the momentary service interruption.
However, a great deal of expenditure is required to install a ZnO element. This approach may be not a perfect measure because the ZnO element tents to be burnt out by a direct hit of lightning to an overhead power line.
Therefore, it is an object of the present invention to provide a low-cost measure for preventing the breaking and the momentary service interruption without the use of the ZnO element so as to reduce the cost of measures for lightning in overhead power lines.
In order to achieve the above object, the present invention provides a creeping discharge lightning protection device in an overhead power line formed of a insulating wire or a bare wire, the creeping discharge lightning protection device comprising a lightning protection device body formed of an insulated wire insulated to the same extent as a power cable and folded into two, the lightning protection device body including an exposed conductor portion and an insulating sheath portion, wherein either one of the exposed conductor portion and the insulating sheath portion is connected to an earth portion of an insulator. Further, in case that the overhead power line is formed of the insulating wire, another one of the exposed conductor portion and the insulating sheath portion is connected to a discharge electrode, wherein the discharge electrode includes a needle electrode which penetrates an insulating sheath of the overhead power line so as to bring about through-breakdown. In case that the overhead power line is formed of the bare wire, another one of the exposed conductor portion and the insulating sheath portion being arranged directly to the overhead power line.
The present invention also provides a creeping discharge lightning protection device in an overhead power line formed of a insulating wire or bare wire, the creeping discharge lightning protection device comprising a lightning protection device body having either one of an insulating layer including a back electrode so as to enhance flashover performance, an insulating tube the one end or both ends of which are opened around a flashover path so as to enhance arc-suppression performance, and combinations thereof so as to enhance flashover performance and arc-suppression performance, wherein the lightning protection device body is positioned between the overhead power line and an earth portion of an insulator.